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Mole Management in Washington Backyards

W A S H I N G T O N S T A T E U N I V E R S I T Y E X T E N S I O N F A C T S H E E T • F S 1 4 6 E

Introduction

Washington State is home to three species of moles, but only two, the Townsend’s mole (Figure 1) and the Pacific mole (Scapanus spp.), cause serious damage to home landscapes in the state. While the “common” or eastern mole (Scalopus sp.), is also a pest, it is not found west of the Rocky Mountains.

Many homeowners mistakenly think moles are rodents—they are NOT! Moles belong to a different mammalian order, the Soricomorpha, which feed mostly on inverte-brates. Damage to flower bulbs and roots in the garden or landscape, is often attributed to moles, but it is usually caused by voles. See Vole Management in Home Backyards and Gardens (Pehling 2013) for information on managing voles.

Moles are serious pests to lawns and gardens in western Washington, along with a few areas east of the Cascade Mountains. The damage caused by moles primarily comes from their tunneling and displacing of dirt. Besides the aesthetic damage to grassy areas, dirt mounds can smother small landscape plants. Tunnels can unearth plant roots, which dry out, or allow rodents (such as voles and mice) access to gnaw on them. Tunnels can also unearth shallow

underground irrigation systems and cover sprinkler heads. In addition, tunnels and mounds can pose a hazard when walking around the home landscape.

Young adults will leave the mother’s territory in the spring and establish new tunnel systems nearby. This behavior can cause the size of the infested areas to grow over time. When combined with the nearly perfect environmental conditions found in western Washington—porous soil and well-watered gardens, lawns, and landscapes—managing these native mammals becomes very difficult. This publica-tion will help home gardeners develop a multi-action plan to deal with moles in the home landscape.

Moles at a Glance

The Townsend’s and Pacific moles range in size from 6 to 9 inches long, have very small eyes, no visible ears, huge front feet, and short, pink tails. The fur is velvety-black. They are rarely seen above ground. Moles are active year-round but are most noticeable and do the most damage during spring and fall.

Voles, which are burrowing rodents, are often mistaken for moles, but can be easily identified by their dark tails and small front feet. To identify various pest’s tunnels, see What’s Tunneling in My Yard (Pehling 2014).

Signs of Damage• Moles damage lawns and landscapes by pushing

up “mole hills” throughout their territories as they excavate tunnels (Figure 2).

• In soft soil, moles often make ridges instead of hills, by simply pushing the soil up and out of their way.

• Townsend’s moles may sometimes feed on bulbs and sprouting seeds or damage them from their tunneling and dirt displacing habits.

Mole Habits• Moles do NOT use their entire tunnel system on a

regular basis, but rotate through different areas of activity.Figure 1. Townsend's mole.

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• Moles are solitary animals, but where one territory ends, another may begin. The mole’s boundaries are defined by scent marking, which is not obvious to humans. When a mole dies, another mole often takes over the tunnel system (Figure 3).

• Territories cover an average area of 2/5 acre (about the size of a square that is 132 feet on each side), and can be any shape (such as long and narrow or circular). Tunnels are often located along sidewalks, fences, or in other non-compacted areas. Well-used old tunnels may not be visible above ground.

• Moles can live up to 3 years in the wild, and females give birth to an average of 3 to 4 young in April or May of each year (Figure 4). About four weeks after birth, the young moles will leave the nest to find its own territory.

• Moles hunt worms and other soil invertebrates that fall into the tunnels, but will also take prey while digging.

• Some Townsend’s moles do take a liking to bulbs, seeds, or grass roots, but in general, voles cause the most damage of this sort.

Management Options

1. Change Your Outlook• Live and Let Live: Adopt a “Live and Let Live”

approach. Consider whether you can just live with a mole in your landscape. Simply raking soil mounds flat or removing the displaced soil will keep the lawn looking good (Figure 5). If you just stomp on the mounds, the mole will push the soil back out. Moles do provide some pest control ben-efits by eating crane fly larvae, cutworms, and even some slugs.

2. Physical Methods• Fencing: Fencing off your property is a difficult and

labor-intensive way to manage moles, but it can be practical for very small lawns. Begin by digging a

Figure 2. A mole run.

Figure 3. Mole territory.

Figure 4. Baby moles.

Figure 5. Remove molehills.

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ditch 18 to 24 inches deep and installing a verti-cal barrier of aluminum sheeting, or ¼ inch mesh galvanized hardware cloth (Figure 6). Bend the bottom few inches outward. If you are installing the barrier where it will not be a hazard, allow six inches to extend above the ground surface. Backfill the ditch. This will only keep moles out; it will not affect moles already inside the fence. Moles may occasionally tunnel underneath the barrier.

• Stomping: During peak mound building (usually spring and fall), stomp down all of the molehills. When you see the mole begin pushing soil back up, use a spade to quickly dig it up and kill it humanely. A sharp blow with the shovel will do the job.

• Flushing: Forcing moles above the ground is possi-ble by pouring several large buckets of water down the active holes all at once. This method is not as effective in sandy soils because the water can drain away inside the tunnels without forcing the moles out. Flushing moles out of holes also requires the assistance of several people.

One method that is not an option is live-capture with the intent to release moles elsewhere. It is against the law in Washington to relocate wildlife off the property. Live-traps are seldom effective in capturing moles.

3. Chemical Methods• Baits: There are several zinc phosphide-based mole

poisons (Figure 7) and several bromethalin-based “gummy worm” baits registered for home use. Results are inconsistent, and even when they do work it may take weeks of treatment to be effec-tive. It is very important to follow all label direc-tions when handling poisonous baits.

• Smoke bombs: These are sometimes effective in dense or water-saturated soils.

• Repellents: Castor oil repellents have shown efficacy on eastern moles, but repellents have not proven effective on western species.

4. Devices • Traps: Live traps of various designs seldom work,

and Washington voters outlawed the use of body-gripping or body-piercing mole traps in 2000 (see RCW 77.15, section 3). While the traps are legal to own, you may NOT use them to trap animals (Figure 8).

• Concussive devices: These devices use blank cartridges or explosive gasses, and are expensive, hazardous, and provide inconsistent results.

• Sonic or vibrating devices: These are generally inef-fective. Moles may still be present even if no new mounds develop. Monitoring runs is necessary to prove a method or device is effective (see Assessing Your Efforts below).

5. Integrated Pest Management• Rotate Methods: Use as many methods as possible

to address the mole problem until you are satisfied. Continue monitoring your landscape as described in Assessing Your Efforts below. Even if you elimi-nate your moles, reinvasion is common.

Figure 6. Mole Barrier. Source: Wildlife Services, Indiana Department of Natural Resources—Division of Fish & Wildlife, and Purdue Extension Entomology.

Figure 7. Mole bait.

Figure 8. Mole traps that use a body-gripping or body-piercing mechanism are not legal to catch animals in Washington.

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Assessing Your Efforts• Monitor your landscape every day before begin-

ning physical or chemical treatments (Figure 9).

• If you find evidence of moles, use a broomstick to punch several holes along the mole tunnel system and in mounds. Repeat the process for several days, and note which holes the moles have repaired.

• Apply your treatment of choice only where you see fresh mole activity.

• If you put in fencing and mounds or tunnels start appearing inside the enclosure, first check the fenc-ing to see if it is damaged or incomplete. Then deal with the moles inside the fenced area before they become established.

• Continue assessing and monitoring the tunnel system after management strategies. Any mole activity indicates failure of the strategies.

Further Reading

Carraway, L. N., L. F. Alexander, and B. J. Verts. 1993. Mammalian Species No. 434. The American Society of Mammalogists. https://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-434-01-0001.pdf.

Dudderar, Glenn R., Tellman, S., and D.K. Elshoff. 1995. The Effectiveness of a New Mole Repellent for Preventing Damage to Lawns by Eastern Moles. Seventh Eastern Wildlife Damage Management Conference. http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1009&context=ewdcc7.

Giger, R. D. 1973. Movements and Homing in Townsend’s Mole near Tillamook, Oregon. J. Mammal 54:648-659. http://www.jstor.org/discover/10.2307/1378964?uid=2129&uid=2&uid=70&uid=4&sid=21102696737871.

Hygnstrom, S.E., R.M. Timm, and G.E. Larson, eds. 1994. Prevention and Control of Wildlife Damage. University of Nebraska-Lincoln. http://icwdm.org/handbook/rodents/ro_b177.pdf.

Ingles, L. G. 1965. Mammals of the Pacific States: California, Oregon and Washington. Palo Alto, CA: Stanford University Press.

Kuhn, L. W., W. Q. Wick, and R. J. Pedersen. 1966. Breeding Nests of Townsend’s Mole in Oregon. J. Mammal 47:239-249. http://www.jstor.org/discover/10.2307/1378120?uid=2129&uid=2&uid=70&uid=4&sid=21102696737871.

Maser, C., B. R. Mate, J. F. Franklin, and C. T. Dyrness. 1981. Natural History of Oregon Coast Mammals. Pacific Northwest Forestry and Range Exp. Station, USDA, Forest Service, Gen. Tech. Rep. PNW-133. 496pp.

Moore, A. W. 1933. Food Habits of Townsend’s and Coast moles. J. Mammal 14:36-40. http://www.jstor.org/discover/10.2307/1374030?uid=2129&uid=2&uid=70&uid=4&sid=21102082079853.

Moore, A. W. 1939. Notes on the Townsend’s Mole. J. Mammal 20:499-501.

Pehling, D.J. 2013. Vole Management in Home Backyards and Gardens. Washington State University Extension Publication FS094E. http://cru.cahe.wsu.edu/CEPublications/FS094E/FS094E.pdf.

Pehling, D.J. 2014. What is Tunneling in My Yard? Washington State University Extension Publication FS143E. http://cru.cahe.wsu.edu/CEPublications/FS143E/FS143E.pdf.

Poche, Richard M. 1997. Mole Census Techniques. Great Plains Wildlife Damage Control Workshop Proceedings. Paper. 375pp. http://digitalcommons.unl.edu/gpwdcwp/375.

Washington State Legislature. 2000. Unlawful Trapping, RCW77.15,194, paragraph 3. http://apps.leg.wa.gov/RCW/default.aspx?cite=77.15.194.

Verts, B. J. and L.N. Carraway. 1998. Land Mammals of Oregon. Berkeley, CA: University of California Press.

Wight, H. M. 1928. Food habits of Townsend’s Mole, Scapanus townsendii (Bachman). J. Mammal 9:19-23. http://www.jstor.org/discover/10.2307/1373352?uid=2129&uid=2&uid=70&uid=4&sid=21102082079853.

Figure 9. Monitoring tunnels.

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By David Pehling, Extension Educator, WSU Snohomish County, Everett, WA.

Copyright 2014 Washington State University

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Issued by Washington State University Extension and the U.S. Department of Agriculture in furtherance of the Acts of May 8 and June 30, 1914. Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, sex, religion, age, color, creed, and national or ethnic origin; physical, mental, or sensory disability; marital status or sexual orientation; and status as a Vietnam-era or disabled veteran. Evidence of noncompliance may be reported through your local WSU Extension office. Trade names have been used to simplify information; no endorsement is intended. Published September 2014.

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